Devices which incorporate the broad concept of controllably dispensing a fluid from a container have been developed. In U.S. Pat No. 3,014,481 to Rumble, Jr., et al. a physiological fluid injection system is shown including a flask and a pair of tubes. A first tube delivers pressurizing air to the inverted bottom of the flask to force fluid out of the flask through a second tube. In U.S. Pat. No. 3,664,549 to Maselli, Jr., a vessel containing liquid is described which can detect when predetermined liquid levels are reached in the vessel. Outflow of the liquid from the vessel, as well as inflow thereto, can be controlled. In U.S. Pat. No. 3,536,449 to Astle a serial dilution apparatus is disclosed which dilutes exact amounts of liquid to form a first dilution while simultaneously providing an exact amount of buffer solution for a succeeding dilution. In U.S. Pat. No. 4,085,780 to Holley, a liquid dispensing system is shown which uses peristaltic squeeze pumps for removing liquid from containers. In U.S. Pat. No. 4,058,146 to Citrin, a system is illustrated for transferring small amounts of liquid from a plurality of containers to a corresponding number of wells in a microtitration test plate.